An aeromagnetic survey over the Shirase Glacier

概要

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The aeromagnetic survey over the Shirase Glacier was for the first time made in 1980 by the 21st Japanese Antarctic Research Expedition. Total force data were acquired in a digital form and reduced to the magnetic anomaly by correcting International Geomagnetic Reference Field and diurnal variations. The obtained anomaly profiles are characterized by low values corresponding to the topographically low area and high values on both sides of the coast in the range from -100 to +300nT. In order to interpret the obtained anomalies, two-dimensional modeling of subglacial topography was made. The obtained model has a trough of 1800-2000m depth with 15-20km width, extending from north to south. The characteristic features of the model topography are consistent with the subglacial topography estimated by the ice-radar and with the sea bottom topography obtained by the echo sounder in the neighboring regions. The magnetic susceptibilities of the rock samples from the eastern regions of the Shirase Glacier were measured in this study. They are mostly in the range of (10)^<-5>-(10)^<-4>emu/cc, though a comparatively larger value of 1-3×(10)^<-3>emu/cc was obtained for the samples from the southernmost rock areas. The constraints of the ground data on the two-dimensional modeling are discussed.
国立極地研究所の論文